July JO. 191V Influence of Grading on Value of Fine Aggregate 267 



Table II. — Proportion of artificially graded sands — Continued 



Laboratory No. 



Proportions. 



C. 



Equivalent mechanical analysis — per cent 

 between — 



and 

 No. 10. 



10 and 20 and 



20. 



30 and 

 40. 



40 and 



Undier 

 No. 5b. 



24 



25 

 26 

 27 

 28 

 29 

 30 

 31 

 32 

 Z2, 

 34 

 35 

 36 

 37 

 38 



39 

 40 



41 



42 



43 

 44 

 45 

 46 



47 

 48 



49 

 50 

 SI 

 52 

 53 

 54 

 55 

 56 

 57 

 58 



59 

 60 



Per ct. 



40 

 30 

 30 

 30 

 30 

 30 

 30 

 30 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 



Per ct. 



60 



o 



10 



20 



30 

 40 



50 

 60 



o 

 10 

 20 



30 

 40 



50 

 60 

 70 

 80 



o 

 10 



20 



30 

 40 



50 

 60 

 70 

 80 



o 



10 



20 



30 

 40 



50 

 60 

 70 

 80 

 90 



100 



Per ct. 



O 

 70 

 60 



50 

 40 



30 

 20 

 10 

 80 

 70 

 60 



50 

 40 



30 

 20 

 10 



o 



90 

 80 

 70 

 60 



50 

 40 



30 



20 



10 



100 



90 

 80 

 70 

 60 



50 

 40 



30 



20 



20 

 o 



6.6 

 10 



16.6 



6.6 

 10 



13-3 

 16.6 

 20 



13-3 

 16.6 



23-3 

 26.6 



6.6 

 10 



13-3 

 16.6 

 20 



23-3 

 26.6 



30 



33-3 



6.6 

 10 



13-3 

 16.6 

 20 



3-3 

 6.6 



23-3 

 26.6 



6.6 

 10 



13-3 

 16.6 

 20 



23-3 



26.6 



o 



3-3 

 6.6 



13-3 

 16.6 



23-3 

 26.6 



3-3 

 6.6 



16.6 



o 



Z-3 

 6.6 

 10 



16.6 



20 



23-3 



26.6 



o 



3-3 

 6.6 

 10 



^Z-Z 

 16.6 

 20 



23-3 

 26.6 



z-z 



6.6 

 10 



U-Z 

 16.6 

 20 



23-3 

 26.6 



30 



33-3 



o 

 70 

 60 



50 

 40 



30 

 20 



70 

 60 



50 

 40 



30 



20 



10 



o 



90 

 80 

 70 

 60 



50 

 40 



30 



20 



10 



100 



90 

 80 

 70 

 60 



50 

 40 



30 



20 



HARDNESS TESTS 



Specimens for the hardness tests were prepared by drilling i-inch cores 

 through the center of the 2-inch cylinders and drying them thoroughly 

 in a hot-air oven. They were tested then for hardness in the same 

 manner as the hardness of rock is obtained, as described above, by 

 holding the ends of the specimens against a revolving steel disk upon 

 which quartz sand was fed as the abrasive. The specimens were 

 weighed carefully before and after 1,000 revolutions of the disk, and the 

 loss in weight was used as an index of the hardness of the mortar. The 

 results of the hardness tests on all the sand mixtures studied are shown 

 98976°— 17 5 



